Synthesis of succinonitrile



puma .13.1940 2,211,240

SYNTHESIS OF SUCCIN'ONI'I'RILE 5 Alexander Douglas Macallum, Niagara Falls, N. Y., assignor to E. I. on Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application August 17, 1938,

Serial No. 225,486

3 Claims. (Cl; 260-464) This invention relates to a, process for preparlutions in ethanol f varying concentrations 0V8! ing succinonitrile, more particularly by react mg 10 u P i an ethylene dihalide with an alkali cyanide.

It has been known that in the preparation of Rcovery of 5 succinonitrile from ethylene dihalides and alkali Alcohol concentration g f ggfizg 5 cyanides, ethanol is an especially suitable reac- 1/ MON added tion medium. The yields, however, have not j been satisfactory, and attempts to improve the 87 -ss.2 yields have so far failed. The best results heretofore have been obtained by adding a boiling concentrated aqueous solution of potassium cy- I anide toan ethanol solution of ethylene bromide. i g g ig of the alcohol .conceptmpiqn on Attempts to increase the yields of this type of e e o e g of my mventlon trated in the following examples. Example 1 reaction by variation of the reaction temperature g 5 and time and of the alcohol concentration Such shows the react on of ethylene dibromide and 15 as with absolutely dry ethanol have failed. sodlum cyamde m 63% .ethanol and the Sec-0nd Applicant discovered the Srprising fact that example shows the reaction of these reactants in a material increase in the yield of succinonitrile 95% ethanol in the reaction of the above described type can Example 1 be obtained by carrying out the reaction in eth- 1500 grams ethylene bromide and 3000 i 20 anol of about 90 to 98% concentration, preierably 95% ethanol were stirred and refluxed g DQ911011? as Teactlon medmm- Th15 litre flask on a steam bath while adding dropwise prising fact seems to be due to the properties of a solution of 750 grams of sodium cyanide in the alkali metal cyanides as well as of succino- 1200 cc" of Wat-en The mixture was refluxed nitrile- S y of the stability of alkah mFtal under stirring for six hours and the formed suc- Cya 111 61911191191 of Yarymg concentmnons cinonitrile was separated from the reaction mix- ShOWed that i mcreasmg alcohol CQnCemYa' ture. The separation of succinonitrile was eftlon the stab y the Cyanide? mcl'easesfected by distilling off a major part of the ethao l'eactlon alkall metal nol and by extracting repeatedly the residue with amdes the ethylene dlhelldes e total methylene chloride under gentle boiling. In this $61199 9 Water 111 the reactwn medmm seems way the methylene chloride extract can be made ache di o as has been Shown by the to float and can be readily siphoned off by suction. fallllles in T use of Pnhydrous ethanol as The methylene chloride extract then was dried action medmm- Applmant has now found a with anhydrous sodium sulfate. The mixture y f out W reaction of ethylene then was filtered and distilled at ordinary .pres- 35 hallde m ik metal cyanide m of sure over steam to recover methylene chloride. th above e l range f concentretlon on the The residue was subjected to fiactional distillaone hand sufilcient stability is attained for the tion t a pressure of 10 n, t The fragraw materials as well as for the final prod c tion distilling at 125-14092. gave a yield of 372 40 40 and on the other hand a sufilcient reaction velocgrams of pure succinonitrile, corresponding to a ity due to the presence of small amounts of wayield of 63% based on the sodium cyanide used. ter can be obtained. It has been found that even Similar results were obtained with 75% ethwhen the amount of water present in the ethanol anol, t e y however, being a er and 001- having a concentration of 90 to 98% is not suffiresponding a yield based on t e cyanide 45 clent to dissolve all the alkali metal cyanide, usedthis amount of water is sumcient to dissolve enough of it in any phase of the reaction and on A mixture of 3000 cc. of 95% ethanol and 1500 formation of succinonitrlle dissolves further grams of ethylene bromide were stirred and reamounts of the alkali metal cyanide, t u D fiuxed in a 12 litre balloon flask on a steam bath, 50 vldlng, sufilclent solvent efiect for the reaction. the reflux condensate having been allowed to run The influence of the alcohol concentration on back into the flask by way of a 2 litre. extraction the stability of sodium cyanide is shown in the flask containing a charge of 750 grains of milled following table, where the results of tests are sodium cyanide. After about 40 hours refluxing shown which were made by refluxing cyanide soand stirring the mixture was cooled and the solids 55 Example 2 iii filtered oil by suction. The filtrates were then evaporated to a small bulls and the residue was treated with methylene chloride and again eva orated. The evaporation residue was again extracted with methylene chloride. The final methylene chloride extract was dried with a few grams of anhydrous sodium sulfate, filtered, evaporated to a small bulk and fractionally distilled as described in Example 1. 1 In the main fraction at 125 to 137 C. and at a pressure of 10 millimeters, 326.4 grams, and in the fraction of the still residue in about thesame temperature range 4; grams of pure succinonitrile were recovered, corresponding to a yield of 90.5% based on the cyanide consumed. 254 grams of unchanged sodium cyanide were recovered in the reflux extraction residue and 6-7 grams of sodium cyanide were recovered from the reaction mixture and could be used in further runs or in any other desired. manner. The higher yield of nitrile obtained here can be attributed to a substantial decrease in the amount of acrylonitrile, sodium succinate, formate, carbonate and. hydrogen cyanide produced as by-products of the succinonitrile in this case.

My invention is not restricted to the specific procedure of the examples, and any other ethylene dihalide, such as ethylene dichloride or alkali metal cyanide, such as potassium cyanide, can he used. However, for best results the use of ethyl ene bromide and of sodium cyanide is to be preierred. It has been found that methylene chloride is an especially advantageous extraction means for the formed succinonitrile, but also any other suitable extraction means may be utilized,

Q5 such as for example ethylene chloride, isopro panel, n-propanol or benzene.

The process of my invention alternatively can be carried out by adding the cyanide directly to the concentrated ethanol halide mixture and stirring the resulting mixture while heating. Thus the reaction time can be substantially decreased, reaction times of 8 hours having been found to be sufficient. While the yield is substantially within the same range as in the above example, it is further possible to add the cyanide or the halide, or the cyanide and the halide, pcrtionwise to the ethanol during the reaction. The reaction temperature can be changed within wide limits, lower as well as higher temperatures being suitable. The amount of ethanol should be mificient to obtain a slurry which can be easily stirred. Moreover, the ethanol can be diluted to a certain degree with water-free inert diluents. Various other modifications will be apparent to those skilled in the art.

I claim:

7.. The process of preparing succinonitrlle com prising boiling a solution of an ethylene dihellde in ethanol of about 99 to 98% concentration, condensing the resulting ethanol vapors, contacting the condensate with a body of finely divided, anhydrous alkali metal cyanide and continuously passing the resulting weal; ethanol solution 01 said cyanide into the aforesaid boiling ethanol solution and continuously boiling said solution until the reaction is substantially complete.

2. The process of preparing succinonitrile com-- prising boiling a solution of an ethylene dihaiide in ethanol of about 95% concentration, condensing the resulting ethanol vapors, contacting the condensate with a body of finely divided, anhydrous alkali metal cyanide and continuously passing the resulting weal: ethanol solution of said cyanide into the aforesaid boiling ethanol solution and continuously boiling said solution until the reaction is substantially complete.

3. The process of preparing succinonitrile comprising bai ing a solution of ethylene dibromide in ethanol of about 95% concentration, condensing the resulting ethanol vapors, contacting the condensate with a body of finely divided, anhydrous sodium cyanide and continuously passing the resulting weak ethanol solution of said cyanide into the aforesaid boiling ethanol solution and continuously boiling said solution until the reaction is substantially complete.

ALEXANDER DOUGLAS MACALLUM. 

